The upgrade from beta1 to rc1 NuGet packages introduced a number of Obsolete members. The messages though are not very helpful:

[Obsolete("This member is obsolete.", true)]
public ClassStatementSyntax Begin { get; }

This just tells the user the member is obsolete but gives them no direction on how to fix the problem. Intellisense is also not helpful here because Begin has no matches. I'm forced to go to the metadata view of the file and search for the new member.

A much better message would be:

[Obsolete("This member is obsolete, use ClassStatement instead", true)]
public ClassStatementSyntax Begin { get; }